A light emitting element such as a semiconductor light emitting diode or injection laser diode is typically mounted on a header such as that disclosed by Backhouse et al in U.S. Pat. No. 3,869,702 issued Mar. 4, 1975. The header is comprised of a steel base plate with a steel stud mounted on a major surface of the plate. The stud is typically threaded so that the device can be mounted on a cooler or other support. The light emitting element is mounted on a second major surface of the base plate or on a copper block which is mounted on the steel base plate.
A light emitting element composed of GaAs and AlGaAs mounted on this header performs well in continuous wave operation with a high yield of useful devices. However, for a light emitting element composed of InP and a quaternary compound such as InGaAsP the yield of useable devices in continuous wave operation is quite low. The reason for this difference is not understood but may be related to a need for better thermal dissipation for diodes containing quarternary compounds.